In recent years, safety performance of automobiles has dramatically improved. In order to avoid a collision with a preceding vehicle, for example, a safety system is proposed in which the distance to the preceding vehicle and the speed of the preceding vehicle are detected and a brake automatically engages in an abnormal approach to the preceding vehicle. In such a system, the distance to the preceding vehicle and the like are measured using a laser radar or a camera. In general, the laser radar or the camera is arranged on the inner side of a windshield, and the measurements are performed by emitting infrared rays ahead.
Incidentally, a measurement device such as the laser radar or the camera as mentioned above is often attached to the inner surface of a glass sheet included in the windshield. In order to conceal such a measurement apparatus from the outside, a mask layer is formed on the inner surface of the glass sheet by applying dark-colored ceramic, and the measurement device is arranged on the mask layer. At this time, an opening is formed in the mask layer, and a laser beam emitted and received by the laser radar, visible light and/or infrared rays received by the camera, and the like are emitted and received through this opening.